Yeah my batts cost 10-20 bucks from Hobbyking but I also use them in my RC cars, RC boats, RC planes and airsoft guns so it's not too bad.
As for the servos, I find the 5645s freak out less often when the bot is being turned on. Being programmable, you can also set them to stay rigid when they lose signal and stuff like that. In my cars and bigger planes, they are a huge difference. Not as huge with a robot, but noticeable.
ARC32 is nice because it's just one board. Never owned a BBII so I can't comment on that, and though I do have an SSC32, I've never managed to get it to do anything useful, but that's just because I'm a terrible programmer.